1. Field of the Invention
This invention is directed to an improved continuous crumbing machine for recycling rubber tires and other materials such as polyethylene containers, gypsum, hardboard, tin cans, glass jars and bottles. The device comprises a pair of rotating rolls having negative rake teeth of interlocking sprocket design formed on the outer periphery of each roll. The materials to be fragmented or crumbed are fed between pairs of rotating rollers having negative rake teeth. A plurality of stages of rotating rollers are placed in series to obtain the desired particle size.
2. Description of the Related Art
The following patents are directed to the crumbing and shredding of rubber tires:
______________________________________ Patent Number Inventor Date ______________________________________ 3,843,061 Hammelmann 1974 4,235,383 Clark 1980 4,614,308 Barclay 1986 4,757,949 Horton 1988. ______________________________________
Barclay & Horton are directed to continuous processes. Barclay employs a plurality of stator blades which intermesh with rotor blades mounted on a central, vertical shaft. The Barclay device is massive, the rotors being about 48 inches in diameter (See Col. 7, lines 16-30 of the Barclay patent).
Horton has transversely disposed cutter wheels on adjacent parallel horizontal shafts. The shafts rotate at different speeds ranging from about 20-34 RPM for the first shaft, and about 26-42 RPM for the second shaft, the speed of the second shaft being about 6 RPM faster.
Horton appears to be the closest reference, but Horton employs cutter wheels instead of negative rake teeth integrally formed into rotating rolls, as in the subject invention. Horton's differential RPM ratio is never as great as the subject invention, which may range from 4:1 to 25:1. Horton obtains particle sizes of one to two inches, and does not mention steel wire removal. In addition, Horton employs cutter wheels instead of negative rake teeth.
Hammelmann's apparatus receives successive tires, stretches them and subjects the tires to a high speed water jet. Clark employs abrasive, counterrotating wheels to disintegrate a tire which is fed into the nip between the wheels in an upright position.